5,484 research outputs found

    The Dynamics of Economic Growth 1985-2000 in Chinese Provinces

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    This paper concerns the provincial growth pattern in China during the period 1985-2000. The hypothesis that provinces with similar growth rates are more spatially clustered than by pure chance is tested. In addition, we test the convergence hypothesis. We find evidence of spatial dependence between neighboring provinces and solve it by including a spatial lag, alternatively a spatial error term, in the growth equation. Other important factors explaining the provincial economic growth are foreign direct investments, infrastructure, preferential policies, and the distribution of industrial enterprises

    Pattern Avoidance in k-ary Heaps

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    In this paper, we consider pattern avoidance in k-ary heaps, where the permutation associated with the heap is found by recording the nodes as they are encountered in a breadth-first search. We enumerate heaps that avoid patterns of length 3 and collections of patterns of length 3, first with binary heaps and then more generally with k-ary heaps

    Upgraded demonstration vehicle task report

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    Vehicle/battery performance capabilities and interface problems that occurred when upgraded developmental batteries were integrated with upgraded versions of comercially available electric vehicles were investigated. Developmental batteries used included nickel zinc batteries, a nickel iron battery, and an improved lead acid battery. Testing of the electric vehicles and upgraded batteries was performed in the complete vehicle system environment to characterize performance and identify problems unique to the vehicle/battery system. Constant speed tests and driving schedule range tests were performed on a chassis dynamometer. The results from these tests of the upgraded batteries and vehicles were compared to performance capabilities for the same vehicles equipped with standard batteries

    Universal Probability Distribution Function for Bursty Transport in Plasma Turbulence

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    Bursty transport phenomena associated with convective motion present universal statistical characteristics among different physical systems. In this letter, a stochastic univariate model and the associated probability distribution function for the description of bursty transport in plasma turbulence is presented. The proposed stochastic process recovers the universal distribution of density fluctuations observed in plasma edge of several magnetic confinement devices and the remarkable scaling between their skewness SS and kurtosis KK. Similar statistical characteristics of variabilities have been also observed in other physical systems that are characterized by convection such as the X-ray fluctuations emitted by the Cygnus X-1 accretion disc plasmas and the sea surface temperature fluctuations.Comment: 10 pages, 5 figure

    The pumpistor: a linearized model of a flux-pumped SQUID for use as a negative-resistance parametric amplifier

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    We describe a circuit model for a flux-driven SQUID. This is useful for developing insight into how these devices perform as active elements in parametric amplifiers. The key concept is that frequency mixing in a flux-pumped SQUID allows for the appearance of an effective negative resistance. In the three-wave, degenerate case treated here, a negative resistance appears only over a certain range of allowed input signal phase. This model readily lends itself to testable predictions of more complicated circuits.Comment: 4 pages, 3 figure

    Neutral gas in Lyman-alpha emitting galaxies Haro 11 and ESO 338-IG04 measured through sodium absorption

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    Context. The Lyman alpha emission line of galaxies is an important tool for finding galaxies at high redshift, and thus probe the structure of the early universe. However, the resonance nature of the line and its sensitivity to dust and neutral gas is still not fully understood. Aims. We present measurements of the velocity, covering fraction and optical depth of neutral gas in front of two well known local blue compact galaxies that show Lyman alpha in emission: ESO 338-IG 04 and Haro 11. We thus test observationally the hypothesis that Lyman alpha can escape through neutral gas by being Doppler shifted out of resonance. Methods. We present integral field spectroscopy from the GIRAFFE/Argus spectrograph at VLT/FLAMES in Paranal, Chile. The excellent wavelength resolution allows us to accurately measure the velocity of the ionized and neutral gas through the H-alpha emission and Na D absorption, which traces the ionized medium and cold interstellar gas, respectively. We also present independent measurements with the VLT/X-shooter spectrograph which confirm our results. Results. For ESO 338-IG04, we measure no significant shift of neutral gas. The best fit velocity is -15 (16) km/s. For Haro 11, we see an outflow from knot B at 44 (13) km/s and infalling gas towards knot C with 32 (12) km/s. Based on the relative strength of the Na D absorption lines, we estimate low covering fractions of neutral gas (down to 10%) in all three cases. Conclusions. The Na D absorption likely occurs in dense clumps with higher column densities than where the bulk of the Ly-alpha scattering takes place. Still, we find no strong correlation between outflowing neutral gas and a high Lyman alpha escape fraction. The Lyman alpha photons from these two galaxies are therefore likely escaping due to a low column density and/or covering fraction.Comment: 9 pages, 3 figure

    Right hemithoracic pseudocyst with splenic artery aneurysm: two rare complications of an uncommon disease

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    Pleural involvement is an uncommon but well recognized complication of chronic pancreatitis, mainly in the form of pleural effusion affecting the left hemithorax. Pancreatic pseudocyst extending to the posterior mediastinum with or without communication with the pleural space is another rare form of this involvement.The treatment of chronic pancreatic pleural effusions and pancreatic pseudocysts generally starts with a conservative approach including bowel rest, drainage of the pleural effusion by repeated thoracentesis or a chest tube, and total parenteral nutrition (TPN) for a period of time determined by the clinical course. Other treatment modalities including percutaneous drainage, endoscopic retrograde cholangiopancreatogram (ERCP) with stenting of the pancreatic duct and surgical drainage are used if conservative approaches fail.We report a patient with a complicated pancreatic pseudocyst who showed an involvement of the posterior mediastinum and right pleural space, with conspectus sparing of the left hemithorax. The patient had a prolonged and complicated course that included recurrence of the pseudocyst with oral feedings and the development of a splenic artery aneurysm. Some of the above findings have been reported separately as uncommon complications of chronic pancreatitis and pancreatic pseudcyst, but to our knowledge a single case with all these complications was not published in the English literature
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